JP4306291B2 - Strobe device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a strobe circuit that controls the light emission operation of a flash discharge tube by switching control of an insulated gate bipolar transistor.
[0002]
[Prior art]
As a strobe circuit that controls the light emission operation of a flash discharge tube by switching (ON, OFF) an insulated gate bipolar transistor (hereinafter referred to as IGBT), for example, a circuit as disclosed in Patent Document 1 Is well known.
[0003]
This strobe circuit has a configuration in which an IGBT is connected in series with a flash discharge tube, and the gate of the IGBT is connected between two transistors connected in series, and is output from a tuning signal output from a tuning signal generator and a dimming circuit. The switching control of the two transistors is performed by the signal to be performed, whereby the voltage supply and non-supply operations to the gate of the IGBT are performed, and the light emission operation of the flash discharge tube is controlled (for example, Patent Document 1). reference.).
[0004]
However, since the conventional strobe circuit controls the light emission of the flash discharge tube based on the two signals of the tuning signal and the light control circuit, the peripheral circuit including the strobe circuit tends to be complicated. Therefore, the strobe circuit shown in FIG. 2 is now mainstream, in which the tuning signal generator and the dimming circuit are integrated into an IC and the light emission control of the flash discharge tube is controlled by one control signal.
[0005]
In FIG. 2, 1 is a flash discharge tube, 2 is an IGBT which is connected in series with the flash discharge tube 1 to control the light emission operation of the flash discharge tube 1, 3 is an input terminal for driving voltage of the flash discharge tube 1, and 4 is an IGBT 2 Q1 is a PNP transistor that controls the voltage supply operation to the gate of the IGBT 2, Q2 is an NPN transistor that controls the voltage non-supply operation to the gate, and 5 is a dimming control circuit ( An input terminal for a control signal output from (not shown), Q3 is an NPN transistor that performs an on / off switching operation according to H (HIGH level signal) / L (LOW level signal) of the control signal, and R1 to R10 are resistors It is.
[0006]
The strobe circuit of this conventional example is characterized in that the transistor Q1 and the resistor R8 constitute a voltage supply circuit to the gate of the IGBT2, and the transistor Q2 and the resistor R9 constitute a voltage non-supply circuit to the gate of the IGBT2. Have.
[0007]
Next, the operation of the conventional strobe circuit will be described.
[0008]
First, when the control signal becomes H, the transistor Q3 is turned on and the transistor Q2 is turned off. When the transistor Q3 is turned on, the transistor Q1 is turned on, and a driving voltage is supplied to the gate of the IGBT 2 via the resistor R8. As a result, the IGBT 2 is turned on and the flash discharge tube 1 emits light.
[0009]
Thereafter, when the amount of light from the flash discharge tube 1 reaches a predetermined amount, a dimming control circuit (not shown) operates and the control signal changes from H to L. Then, on the contrary, the transistor Q3 and the transistor Q1 are turned off and the transistor Q2 is turned on. When the transistor Q1 is turned off, the supply of the driving voltage to the gate of the IGBT 2 is stopped. When the transistor Q2 is turned on, the gate of the IGBT 2 is grounded through the resistor R9, and the IGBT 2 is turned off. When the IGBT 2 is turned off, the flash discharge tube 1 stops emitting light.
[0010]
In the conventional strobe circuit, since the voltage supply circuit and the voltage non-supply circuit are formed independently, both of the transistors Q1 and Q2 that are inevitably generated when the flash discharge tube is repeatedly emitted and stopped. Even in the state where both are turned on, the voltage supply / non-supply operation to the gate of the IGBT 2 is intended to be performed with good balance and stability.
[0011]
[Patent Document 1]
Japanese Patent Laid-Open No. 10-246907
[Problems to be solved by the invention]
However, since the switching control of the IGBT 2 depends on the adjustment values of the resistors R8 and R9, chattering occurs, and there is a possibility that the IGBT 2 is damaged due to the influence. In addition, in the lines of the resistors R3, R6, and R7 (Q2), current always flows regardless of the on / off state of the transistor Q3. Therefore, there is a problem that power consumption is large and battery life is shortened.
[0013]
The present invention solves the above-described problems of the prior art, and an object of the present invention is to provide a strobe circuit that can stably control an IGBT and has low power consumption.
[0014]
[Means for Solving the Problems]
In order to solve the above problems, the strobe circuit of the present invention has the following configuration.
[0015]
The invention according to claim 1 includes a flash discharge tube, an insulated gate bipolar transistor connected in series to the flash discharge tube and performing light emission control of the flash discharge tube by switching control, and a gate of the insulated gate bipolar transistor A first transistor for controlling voltage supply to the gate, a second transistor for controlling voltage supply to the gate, connected to the gate of the insulated gate bipolar transistor, and an external In a strobe circuit including a third transistor that is switched by a light emission control signal, the strobe circuit is connected between the base of the second transistor and the collector of the third transistor, and the third transistor is off. Charged and stored by charging when the third transistor is on. A strobe circuit, characterized in that it comprises a capacitor for discharging through said third transistor to charge.
[0016]
According to the invention having the above-described configuration, an unnecessary current flow is provided by providing the capacitor that charges when the third transistor is off and discharges the accumulated charge when the third transistor is on. It can be cut off and power consumption can be reduced. Further, since the accuracy of the switching control of the second transistor is improved, the accuracy of the IGBT switching control is improved, and the voltage supply / non-supply operation to the gate can be performed in a balanced and stable manner.
[0017]
The invention according to claim 2 includes a diode having an anode connected to an emitter of the third transistor, and a resistor connected between a cathode of the diode and the capacitor, the diode, 2. The strobe circuit according to claim 1, wherein a circuit formed by the resistor, the capacitor, and the third transistor is a discharge circuit of the capacitor.
[0018]
By forming such a discharge circuit, when the third transistor is turned on (the on state is a very short time), the discharge of the charge accumulated in the capacitor is completed smoothly.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a gaming machine according to the present invention will be described with reference to the accompanying drawings.
[0020]
FIG. 1 is a diagram showing a configuration of a strobe circuit in the present embodiment.
[0021]
In FIG. 1, 1 is a flash discharge tube filled with xenon gas, 2 is an IGBT connected in series with the flash discharge tube 1 to control the light emission operation of the flash discharge tube 1, and 3 is for driving the flash discharge tube 1 An input terminal for inputting voltage, 4 is an input terminal for driving voltage of the IGBT 2, Q1 is a PNP transistor for controlling a voltage supply operation to the gate of the IGBT 2, and Q2 is an NPN type for controlling a voltage non-supply operation to the gate. The transistor 5 includes an input terminal for a control signal output from a dimming control circuit (not shown), and Q3 performs an on / off switching operation according to the control signal H (HIGH level signal) / L (LOW level signal). The NPN transistor C1 is charged when the transistor Q3 is off, and the accumulated charge is discharged when the transistor Q3 is on. Capacitor which, D1 is a diode, R1 to R10 denote resistors. The diode D1 and the resistor R6 become part of a current path formed during discharge.
[0022]
The transistor Q1 constitutes a first transistor, the transistor Q2 constitutes a second transistor, and the transistor Q3 constitutes a third transistor.
[0023]
Next, the operation of the strobe circuit of this embodiment will be described.
[0024]
First, when the control signal from the dimming control circuit becomes H (emission command), the transistor Q3 is turned on, the transistor Q1 is turned on, and the driving voltage is supplied to the gate of the IGBT 2 via the resistor R9. . As a result, the IGBT 2 is turned on and the flash discharge tube 1 emits light.
[0025]
At the same time, the discharge of the charge accumulated in the capacitor C1 while the transistor Q3 is off is started. At this time, a discharge path including a diode D1, a resistor R6, a capacitor C1, and a transistor Q3 is formed to smoothly complete discharge while the transistor Q3 is on.
[0026]
Thereafter, when the amount of light from the flash discharge tube 1 reaches a predetermined amount, the dimming control circuit operates and the control signal changes from H to L (light emission stop command). Then, the transistor Q3 is turned off and the transistor Q1 is also turned off. Then, the supply of the driving voltage to the gate of the IGBT 2 is stopped.
[0027]
At the same time, the capacitor C1 starts to be charged, while the transistor Q2 is turned on. Then, the gate of the IGBT 2 is grounded through the resistor R9, and the IGBT 2 is turned off. When the IGBT 2 is turned off, the flash discharge tube 1 stops emitting light.
[0028]
Thereafter, when the charging of the capacitor C1 is completed, the flow of current passing through the resistor R7 is cut off, and Q2 is turned off.
[0029]
As described above, according to the strobe circuit of the present embodiment, charging is performed when the transistor Q3 is off, and the capacitor C1 that discharges the accumulated charge when the transistor Q3 is on is provided, thereby blocking unnecessary current flow. , Power consumption can be reduced.
[0030]
For example, when applied to a digital camera that consumes more power than a silver halide camera, the effect of extending the battery life can be expected.
[0031]
In addition, since the capacitor C1 is charged and discharged according to the switching operation of the transistor Q3, the switching control of the transistor Q2 is accurately performed, thereby improving the accuracy of the switching control of the IGBT 2 and supplying or not supplying voltage to the gate. The operation is balanced and stable.
[0032]
【The invention's effect】
As described above, the strobe circuit according to the present invention has the effects of stabilizing IGBT control, preventing IGBT breakdown due to chattering, and reducing power consumption.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a strobe circuit according to an embodiment of the present invention. FIG. 2 is a diagram showing a configuration of a strobe circuit of a conventional example.
1 Flash discharge tube 2 IGBT
3, 4 Voltage input terminal 5 Signal input terminal Q1 First transistor Q2 Second transistor Q3 Third transistor C1 Capacitor D1 Diodes R1 to R10 Resistance

Claims (2)

A flash discharge tube, an insulated gate bipolar transistor connected in series to the flash discharge tube and performing light emission control of the flash discharge tube by switching control, a gate connected to the gate of the insulated gate bipolar transistor, and a voltage to the gate A switching operation is performed by a first transistor that performs supply control, a second transistor that is connected to the gate of the insulated gate bipolar transistor, and that controls voltage non-supply to the gate, and a light emission control signal from the outside. In a strobe circuit having a third transistor ,
Charge connected between the base of the second transistor and the collector of the third transistor, and charged when the third transistor is off, and accumulated by charging when the third transistor is on flash circuit, characterized in that it comprises a capacitor for discharging through said third transistor. A diode having an anode connected to the emitter of the third transistor, and a resistor connected between the cathode of the diode and the capacitor, the diode, the resistor, the capacitor, and the third transistor The strobe circuit according to claim 1, wherein the formed circuit is a discharge circuit of the capacitor.

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